Vertical takeoff and landing (VTOL) aircraft employ ducted fan units or powered rotors (e.g., tiltrotors) that generate vertical lift for hovering the aircraft during takeoff and landing. A ducted fan unit includes a ducted fan or propeller disposed within a duct or shroud formed in a body of the aircraft. The fan draws air into an inlet opening of the duct and propels the air at a high speed out of an outlet opening of the duct, which is typically facing downward toward the ground. The vertical thrust generated by the ducted fan unit lifts the aircraft from the ground. Once hovering, the aircraft may employ one or more propulsion generators (e.g., engines) to produce forward thrust.